Danielle Baskin is an entrepreneur who lives in San Francisco. She's an avid bicyclist in a city that tries to be bike-friendly. There's a bike lane in the popular Valencia Street. And by "in", I don't mean "alongside." I mean right in the middle of the road.
I gather that this choice is suboptimal from the perspective of the city's bicyclists. The city government has placed signs along various points of the lane, expressing a desire that its users be safe. But also, apparently, demonstrating an awareness of the limitations of the road design.
You can see many of these signs at Baskin's Twitter feed.